x86, efi: Break up large initrd reads

The efi boot stub tries to read the entire initrd in 1 go, however
some efi implementations hang if too much if asked to read too much
data at the same time. After some experimentation I found out that my
asrock p67 board will hang if asked to read chunks of 4MiB, so use a
safe value.

elilo reads in chunks of 16KiB, but since that requires many read
calls I use a value of 1 MiB.  hpa suggested adding individual
blacklists for when systems are found where this value causes a crash.

Signed-off-by: Maarten Lankhorst <m.b.lankhorst@gmail.com>
Link: http://lkml.kernel.org/r/4EEB3A02.3090201@gmail.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

2 files changed, 15 insertions, 6 deletions

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 4055e63d0b04..fec216f4fbc3 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -643,14 +643,22 @@ grow:
                         u64 size;
 
                         size = initrds[j].size;
-                        status = efi_call_phys3(fh->read, initrds[j].handle,
-                                                &size, addr);
-                        if (status != EFI_SUCCESS)
-                                goto free_initrd_total;
+                        while (size) {
+                                u64 chunksize;
+                                if (size > EFI_READ_CHUNK_SIZE)
+                                        chunksize = EFI_READ_CHUNK_SIZE;
+                                else
+                                        chunksize = size;
+                                status = efi_call_phys3(fh->read,
+                                                        initrds[j].handle,
+                                                        &chunksize, addr);
+                                if (status != EFI_SUCCESS)
+                                        goto free_initrd_total;
+                                addr += chunksize;
+                                size -= chunksize;
+                        }
 
                         efi_call_phys1(fh->close, initrds[j].handle);
-
-                        addr += size;
                 }
 
         }
diff --git a/arch/x86/boot/compressed/eboot.h b/arch/x86/boot/compressed/eboot.h
index f66d023e91ef..39251663e65b 100644
--- a/arch/x86/boot/compressed/eboot.h
+++ b/arch/x86/boot/compressed/eboot.h
@@ -12,6 +12,7 @@
 #define DESC_TYPE_CODE_DATA     (1 << 0)
 
 #define EFI_PAGE_SIZE           (1UL << EFI_PAGE_SHIFT)
+#define EFI_READ_CHUNK_SIZE     (1024 * 1024)
 
 #define PIXEL_RGB_RESERVED_8BIT_PER_COLOR               0
 #define PIXEL_BGR_RESERVED_8BIT_PER_COLOR               1